Magnetic Resonance Imaging (MRI) is a known examination technique for generating images of the inside of a body of a patient, and is based on the physical phenomenon of magnetic resonance (MR). A magnetic resonance device includes, for this purpose, a transmitting system, with which radio frequency (RF) electromagnetic excitation pulses, (also called RF pulses), may be generated which are irradiated into the patient during a magnetic resonance scan. U.S. Patent Application Publication No. 2014/0347054 A1, U.S. Pat. No. 8,901,929 B2, and German Patent No. DE 10 2012 210 280 B4 disclose, by way of example, various embodiments of a transmitting system. From the RF irradiation, a magnetic alternating field results having a transmit frequency, which is also called the B1 field. The irradiated excitation pulses are capable of deflecting nuclear spins in order to obtain a desired flip angle distribution for the respective examination. The deflected nuclear spins in turn emit MR signals, which are measured by the magnetic resonance device.
The transmitting system includes at least one RF antenna, which may also be called a RF transmitting antenna. The RF transmitting antenna is operated, for example, by at least one RF amplifier. The at least one RF amplifier transmits a transmission signal by a RF transmitting voltage to the RF transmitting antenna. The transmission signal has, for example, a sinusoidal shape having a particular transmit frequency, which is limited by an envelope, (e.g., a rectangular or Gaussian curve).
Scaling of the RF transmitting voltage for the RF pulses may be based on a reference voltage obtained in advance by a scan on the respective patient. During this scan, RF pulses are generated by transmission signals whose transmit frequency is the center frequency of the transmitting system. During recording of imaging scan data that follows the scaling, the problem occurs of the image quality may be inadequate in the case of excitation by RF pulses that are played at a different transmit frequency to the center frequency.